Water ski



J. M. HARTMAN WATER SKI Filed Feb. 21, 1944 INVBVTOR.

ATTORNEY Patented Aug. 14, 1945 UNITE-D STATES PATENT OFFICE WATER SKI John M. Hartman, Glendale, Calif.

Application February 21, 1944, Serial No. 523,208

6 Claims.

At all average speeds, this straight bottom surface may be in contact with the water throughout the greater portion of the length of the surface, and accordingly the resistance or frictional drag offered by the ski is in rather direct proportion to the length and area of its water contacting surface- With the ordinary ski, this frictional drag is relatively great, and the ski lacks desirable supporting or buoyant effect due to the greater tendency, as compared with the invention, not only of the forward portion but also of the rear portion of the ski to ride more deeply in the water.

The primary objects of the invention are to provide certain distinct variations in the shape of the bottom surface of the ski, to the end that its frictional resistance to forward movement through the water will be considerably lessened, and the weight supporting capacity of the ski during movement, will be increased to the eigtent of permitting substantial reductions of either or both the required length and width of the ski.

In accordance with the invention, the bottom surface of the ski is given an irregular or stepped form presenting a lower surface portion extending from an intermediate location to the curved front of the ski, and a rearward extending portion offset upwardly with relation to the forward surface. Preferably, the offset portions of the bottom surface are substantially parallel and extend straight, longitudinally of the ski, with an abrupt interruption or shoulder formed at the point of offset between the surfaces. By virtue of this bottom surface formation, a considerable length of the surface directly beyond the rear of the forward surface section rides out of the water, thus lessening the area of Water contact and the frictional drag. Though to a lesser degree, a ski thus formed materially contributes to a reduction of frictional resistance by reason of its tendency to ride out of the water further toward the rear of the ski. Greater supporting or lifting capacity results from the tendency of the ski, by

reason of its stepped bottom surface, to ride higher in the water and at increased inclination toward the rear.

The invention contemplates various additional features and advantages, such as the provision of openings in the ski for admitting air to its under surface to relieve what otherwise would be the undesirable effects of an evacuated condition in the recess or area at the rear of the shoulder or interruption between the offset surfaces. All such features, as well as the objects specifically referred to in the foregoing, will be understood more fully from the description to follow, and the I accompanying drawing, in which: I

Fig. 1 is a' view showing the ski in side elevation; Fig. 2 is a bottom view of the ski; and f f Fig. 3 is a fragmentary section on line 3--3 of Fig. 2. y

Referring first to Fig. 1, it will be understood that the body In of the ski may be provided with any suitable foot attachment or supporting means. Merely' as illustrative, such means is shown to comprise a forward or toe section II and a heel support I2, the two bein positioned longitudinally of the ski at a location affording the proper balance. The bottom rear surface of the ski is shown to carry a rudder fin l3 for the apparent purpose of guiding the ski in a straight line of movement within the water.

It will be understood that the body l0 of the ski may be made in any suitable manner to have the regular bottom surface shape or stepped configuration referred to in the foregoing. Typically and preferably, the ski comprises two wooden sections l4 and IS in overlapping relation and ecured together at the overlap by suitable means, not shown, such as wooden pegs, screws and the like. The forward sectionv l4, having the up-turned end Ma, terminates at a point near or somewhat forward of the longitudinal center of the ski, the end of the section forming a shoulder l6 so that the bottom surfaces I1 and 18 may be said to have stepped relation. Although in its broader aspects the invention is not necessarily so limited, it is preferred that the forward section end form substantially a right angle shoulder at I6, thus giving an abrupt break in the continuity of the surfaces I1 and I8.

When ridden in the water at an average speed, the ski is, submerged toward the rear with the forward portion riding out of the water. The surface of the water with relation to the ski may be taken to be substantially as illustrated by the position of the dash line WW. It will be observed that a portion of the bottom surface at;

l'9 extending rearwardly from the shoulder l6, rides out of the water. The tendency is for an evacuated condition to be created within the space or recess at 20 defined by the shoulder l6, surface l9 and the surface of the water. In order to relieve this condition, the space is suitably vented, as by means of openings 2| drilled angularly through the body of the ski and the shoulder along its forward extent, again due to the described stepped formation.

I claim: 1. A water skicomprising joined forward and rearward sections in overlapping arrangement, 1 said forward section having an upwardly turned end and said rearward section having a bottom surface offset upwardly from the bottom surface of saidforward section, the rearward end of the forward: section forming an abrupt shoulder betweensaid surfaces. and means for admitting air through the ski to the underside thereof at the rear of said-forward section.

2. Aiwater ski comprising. a body having a forward bottom surface and a rearwardly extending bottom surface offset upwardly from saidforward surface with suificient abruptness that an air 1 space exists at the location of the offset Whenthe ski is in motion in the water,..and means" for venting air from v of the ski.

said'space through the body 3. A water skicomprising a body having a for- In this latter regard, the load supporting characterisitcs of the ski are materially improved by reason: of the greater lift straight longitudinally and extends to the upwardly turned front end of the ski, and a rearward bottom surface offset upwardly from said forward surface and extending substantially parallel therewith to the rear end of the ski, the offset between said shoulders being sufficiently abrupt that an air space exists at the location of the shoulder when the ski is in motion in the water, and means for venting air from said space through the body of the.ski.-

4. Awater ski comprisinga body having a forward bottom surface and a rearwardly extending bottom surface offset upwardly from said surface, and a shoulder between said surfaces, there being an opening extending within the ski from its top surface and through the bottom only at the rear of said forward surface and in'close proximity to saidshoulder.

' ward bottom surface which issubstantially 5. A water ski comprising a body having a forwardbottom surface and a rearwardly extending bottomsurface offset upwardly from saidforward surface, and a shoulder between said: surfaces,

surface and said rearward section having abottom surface extending substantially parallel with and offset upwardly from the bottom surface 'of. said. forward section to form a shoulder extending straight across the ski. and. having suflicient-abruptness that an air space exists at the I location ofthe offsetwhen the ski is in-motion in the water, andimeans'for venting air from said space through the body of the-ski.

JOHN Ml HARTMAN. 1 

